Passive self-alignment technique for array laser transmitters and receivers for fiber optic applications

ABSTRACT

A method of terminating multiple optical fibers, by placing terminal ends of the fibers into a connector to create a fiber end face array, locating a plurality of optical devices on a substrate in an array having a matching geometry as the fiber end face array, and positioning the connector with respect to the substrate to align the fiber end face array with the optical device array. The optical device substrate can be formed as part of a fiber termination fixture which further includes a carrier having two holes adapted to receive respective alignment pins of the connector. The optical device substrate is advantageously affixed to the carrier by forming a first solder ball contact array pattern on a surface of the optical device substrate, forming a second solder ball contact array pattern on a surface of the carrier, wherein the second solder ball contact array pattern matches the first solder ball contact array pattern, and melting a plurality of solder balls disposed between the first solder ball contact array pattern of the optical device substrate and the second solder ball contact array pattern of the carrier such that solder reflow self-aligns the patterns, and further positions the optical device array in a predetermined orientation with respect to the alignment holes in the carrier.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to the interconnection ofoptical devices and optical media, and more particularly to a method ofpassive self-alignment of an array of active optical devices (e.g.,laser drivers and photodetectors) to a corresponding array of opticalfibers. The method also allows for the integration of other electroniccomponents, such as amplifier drivers, in the interconnection.

2. Description of Related Art

Optical fibers have replaced copper wire in recent years as thepreferred medium for carrying telecommunications and data signals, dueto the high efficiency of optical data transmission. As with copperwire, it is necessary to provide for the interconnection of opticalfibers, during installation, repair or replacement of the fibers, and toterminate the fibers onto active optical devices.

Optical devices include, for example, optical sensors (photoelectricdiodes or photodetectors) and light sources (typically solid-statedevices, such as light-emitting diodes (LEDs) or laser diodes). Thetermination of an optical fiber may be indirect, i.e., the fiber may beconnected to some other (passive) optical device such as a beam splitteror polarizer, before the light beam is directed to the active opticaldevice.

There are generally two kinds of optical interconnection devices,splices and connectors. The term “splice”, usually refers to a devicewhich provides a permanent connection between a pair of optical fibers(i.e., a connection that is not intended to be removable). Many fiberoptic splices employ plate elements having fiber-receiving V-shapedgrooves, with means provided for clamping the terminal ends of a pair offibers in a common groove. Some of these devices are designed tointerconnect a plurality of pairs of fibers; see, e.g., U.S. Pat. No.5,151,964.

The term “connector,” in contrast, usually refers to a device which maybe engaged and disengaged repeatedly, often between different plugs andreceptacles. Connectors also can be used to removably interconnect aplurality of pairs of fibers; see, e.g., U.S. Pat. No. 5,381,498. Thepresent invention is generally related to such devices, although theterm “connector” should not be construed in a limiting sense, since thepresent invention may inherently provide a permanent, as well astemporary connection/termination.

There are two primary types of commercially available fiber opticconnectors, namely, ferrule connectors and bionic connectors. Ferruleconnectors use a ferrule plug, typically ceramic, having a central borewhich receives a single optical fiber. Bionic connectors use a plug inthe shape of a truncated cone. Both connectors usually combine a pair ofplugs fitting into a common socket or receptacle to provide a completedconnection. The prior art includes hybrid ferrule connector/splices,such as those shown in U.S. Pat. Nos. 4,986,626 and 5,159,655.

One area which has not been adequately addressed by the prior art,however, is the interconnection, or termination, of an array of opticalfibers to a corresponding array of active optical devices. Since theplugs of ferrule and bionic connectors receive only a single fiber, arelatively large bank of such connectors must be provided to terminateseveral fibers. One drawback with multifiber connectors is the poorinterconnection densities that are achieved. While some ferrule designshave densities around 2 connections per square centimeter, this may becompared to densities of 4 connections or more per square centimeter insome copper wire connectors, such as an RJ45 connector. Some nonferruledesigns provide slightly improved densities, such as that described inU.S. Pat. No. 4,045,121, but that connector has far too many parts andis not easily installed. A simpler multifiber connector is depicted inEuropean Patent Application No. 514,722 (commonly referred to as an “MT”connector).

Fiber alignment is also a problem when terminating an array of fibers atrespective optical devices. Each fiber must not only be properly alignedtransversely, i.e., with the fiber tip precisely located at the emitteror receiver of the active device, but must further be positioned in theproper angular orientation to ensure that the light beam exits/entersthe fiber in an optimum direction with respect to the device. Any airgap between the endface of an optical fiber and the optical surface of arespective active device should also be minimized in order to reducetransmission losses across the interface. Accurate alignment of fiberswith active devices is thus a tedious and time-consuming process.

In order to discover the best position/orient ation, active alignmenttechniques detect actual transmission of optical signals across thedevice-fiber interface. For optical sensors, active alignment isaccomplished by transmitting a signal through the fiber to the sensor,and then monitoring the sensor output while moving the terminal end ofthe fiber, or other alignment element. The signal can be fed into theother (distal) end of the fiber, or injected at an intermediate pointusing a “clip-on” instrument that creates a microbend in the fiber atthe injection point.

For light sources, active alignment is accomplished by powering up thedevice, and then monitoring the signal that flows though the fiber whilemoving the terminal end of the fiber or other alignment element. Thesignal can be monitored by sensing the output at the distal end of thefiber, or by picking the signal off at an intermediate point using aclip-on instrument. For either type of optical device (transmitter orreceiver), active alignment thus requires extensive instrumentation.

Another problem in terminating optical fibers relates to the widedissimilarities in the myriad connector styles. Because of the differentsizes and geometries of connector bodies, ferrules, and othercomponents, any technique adapted for use with one particular connectoris generally incompatible with other connector designs. Special adapterskits or jumper cables may be necessary to achieve compatibility.

In light of the foregoing, it would be desirable to devise an improvedmethod of terminating an array of optical fibers to an array of opticaldevices, which allows for the passive self-alignment of the device arrayto the optical fiber array. It would be further advantageous if themethod accommodated higher interconnection densities, and were generallyusable with any commercially available fiber optic connector.

SUMMARY OF THE INVENTION

It is therefore one object of the present invention to provide animproved method of interconnecting or terminating a plurality of opticalfibers with a plurality of respective active optical devices.

It is another object of the present invention to provide such a methodthat allows for the passive selfalignment of the optical fibers to theoptical devices.

It is yet another object of the present invention to provide highlyintegrated, low profile fiber optic array transmitters and receivers forultra-high bandwidth data distribution and communication.

A further object of this approach is to establish a precisely definedinterface, with respects to physical separation, between the active(photonic) device apertures and the plurality optical fiber termination.The interface permits a precise uniform physical separation of less than0.15 mm to be achieved across all emitter and/or detector apertureswithout physically bonding via an adhesive to the optical fiberconnector termination. This reduces the dependency on requiring narrowbeam divergence emitters and reduces loss in the detector to fibertermination due to bean divergence.

Still another object is the increase in design flexibility by allowingthe optical (emitter/detector) to electrical interface assembly to bepre-fabricated and subsequently inserted into the desired packagehousing of choice. This eliminates the need for customization when usedwith commercial optical multi-fiber connectors (ferrules).

Yet another objective is the protective laminate interface between theactive emitter/detector and the optical fiber termination. This makesthe technique directly applicable to reduced failure risk in harshenvironments such as military avionics.

The foregoing objects are achieved in a method of terminating aplurality of optical fibers, generally comprising the steps of placingterminal ends of the optical fibers into a connector to create a fiberend face array, locating a plurality of optical devices on a substrate,the optical devices being arranged in an array having a matchinggeometry as the fiber end face array, and positioning the connector withrespect to the substrate to align the fiber end face array with theoptical device array. The optical device substrate can be formed as partof a fiber termination fixture which further includes a carrier havingmeans for aligning the carrier with the multifiber connector. Thealigning means can take the form of two holes formed in the carrier andadapted to receive respective alignment pins of the connector. Theoptical device substrate is advantageously affixed to the carrier byforming a first solder ball contact array pattern on a surface of theoptical device substrate, forming a second solder ball contact arraypattern on a surface of the carrier, wherein the second solder ballcontact array pattern matches the first solder ball contact arraypattern, and melting a plurality of solder balls disposed between thefirst solder ball contact array pattern of the optical device substrateand the second solder ball contact array pattern of the carrier suchthat solder reflow self-aligns the patterns, and further positions theoptical device array in a predetermined orientation with respect to thealignment holes in the carrier. The carrier can be thermally enhanced toact as a heat sink when melting the solder balls. In the illustrativeembodiment, the optical devices are active optical devices, such asphotodetectors or light emitters. The electrical contacts to the opticaldevices are made either during or after the chip to carrier attachment.The carrier can include electrical point-to-point connections, whichallow optical devices possessing electrical contacts on the devicefrontside, the device backside, or a combination of frontside andbackside contacts, to be used. A housing may be provided to support thefiber termination fixture in a predefined location and orientation withrespect to a hole formed in the housing which receives the connector.

The above as well as additional objectives, features, and advantages ofthe present invention will become apparent in the following detailedwritten description.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further objectives, and advantages thereof,will best be understood by reference to the following detaileddescription of an illustrative embodiment when read in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a perspective view of one embodiment of an active deviceterminal for an array of optical fibers, constructed in accordance withthe present invention;

FIG. 2A is a front elevational view of an alignment carrier which ispart of a termination fixture used by the active device terminal of FIG.1;

FIG. 2B is a top plan view of the alignment carrier of FIG. 2A;

FIG. 2C is a bottom plan view of an active device chip which is alsopart of the termination fixture;

FIG. 2D is a front elevational view of the assembled termination fixtureusing the alignment carrier of FIGS. 2A-2B and the active device chip ofFIG. 2C; and

FIG. 2E is a partial top view that shows the active optical chip andcarrier assembly attached to the flex Interconnect, and

FIG. 2F is a front view of FIG. 2E.

FIG. 3 is a perspective view illustrating deployment of an active deviceterminal of the present invention within a housing that also serves toretain a multifiber connector; and

FIG. 4 is a top plan view illustrating pick-and-place production ofcarriers having active emitter/detectors according to the presentinvention.

DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

With reference now to the figures, and in particular with reference toFIG. 1, there is depicted one embodiment 10 of an active device terminalconstructed in accordance with the present invention. Terminal 10includes a driver or receiver circuit module 12, a fiber terminationfixture 14, and a flex circuit 16 operatively connecting fibertermination fixture 14 to circuit module 12.

Circuit module 12 includes an electrically insulative substrate orcircuit board 18 upon which conventional electronic components 20 aremounted, according to the use of the device as either a transmitter or areceiver. Where terminal 10 is a transmitter, circuit module 12 hasamplifiers and drivers for the solid-state light sources described belowin fiber termination fixture 14. Where terminal 10 is a receiver,circuit module 12 has amplifier and pre-amplifier receiver electronicsfor the optical sensors described below in fiber termination fixture 14.Electronic components 20 are preferably surface-mounted on circuit board18, but may be mounted using lead-through pins. In the illustrativeembodiment, circuit module 12 has twelve ports (inputs for a receiver,outputs for a transmitter), corresponding to twelve optical fibers whichare to be connected to termination fixture 14, for twelve different datasignals.

Termination fixture 14 is generally comprised of an active device chip22, and an alignment carrier 24 which are discussed further below inconjunction with FIGS. 2A-2F.

Flex circuit 16 includes a generally rectangular substrate or sheet 26,preferably constructed of a flexible, electrically insulative polymericmaterial such as polyamide, having a plurality of conductive (copper)leads, or traces and conductive planes 28 formed on one or more layersthereon, such as by using a phototeching and lamination process. A giventrace 28 has conductive pads at each end to facilitate electricalconnection to one of the ports of circuit module 12 at one end, and to acontact formed on active device chip 22 at the other end. The number ofsuch traces 28 on flex circuit 16 depends upon the type of device beingused. For a transmitter, twelve traces are provided which are connectedto respective contacts for twelve solid-state emitters located on activedevice chip 22. These contacts are the anodes (p-contacts) of theemitters; a common cathode (n-contact) is provided for the emitterarray, and contact with the cathode is made on the backside of activedevice chip and is an integral part of the mechanical alignment contactsbetween the device chip and the carrier 22, 24. For a common cathodediode receiver chip a similar 12 trace laminate flex sheet 26 may beused to contact the anodes, and a conductive plane layer used to contactthe cathode. When using isolated anode and cathode optical components,or metal-semiconductor-metal (MSM) receiver devices, 24 traces orcontacts are provided, two for each of the twelve solid-statetransmitter/receiver location on the active device chip, on one or moreflex layers. In addition to the bond provided by the electricalconnection between the trace pads and the circuit module ports or activedevice chip contacts, a further physical bond may be provided betweensheet 26 and circuit board 18 or active device chip 22 using, e.g., anadhesive, such as an acrylate or silicon-based adhesive.

Flex circuit 16 is designed to support a high-frequency connection,particularly frequencies of five Gbit/sec or more. Flex circuit 16 isalso designed to provide impedance matching with the ports of circuitmodule 12 and the active devices on chip 22.

The construction of termination fixture 14 may be understood by furtherreference to FIGS. 2A-2F. FIGS. 2A and 2B depict one embodiment ofalignment carrier 24, that is specifically adapted for use with the MTconnector mentioned in the Background. Alignment carrier 24 is generallya rectangular block, containing alignment pin holes 34, with dimensionsand tolerances based on a predefined commercial or custom optical fiberarray connector, e.g. MT connector. The alignment carrier is fitted witha solder “ball” contact pad array 30 on the upper surface, thereof,comprising a plurality of solder contacts 32. The contact pad arrayforms an arbitrary pattern, which identifies and maintains a specificpre-defined optical component alignment and orientation relative to thecarrier alignment pinholes 34. Either pre-molding, drilling, reactiveetching or ion milling processes can be used to form the carrier 24alignment pinholes 34. The manufacturing process used depends on thematerial used for the carrier based. Plastic and metal carrierbase-materials support molding and drilling manufacturing processes.Ceramic and glass carrier base materials support drilling and etching.Semiconductor carrier base-material support drilling, reactive etching,and ion milling. The carrier contact pad array is located relative tothe alignment pinholes, and formed, thereon, such as by usingelectro-deposited metal, electroplating, and photolithography processes.The carrier base material may be thermally enhanced in order to functionas a heat sink.

The flex circuit 16 is typically attached to the optical device andcarrier assembly, FIG. 2D, after the optical device has been solderreflow attached to the carrier and the critical optical deviceapertures, FIG. 2E and 44, to carrier alignment pin hole 34 toleranceshave been established. Either the optical chip contact array pads or thealignment carrier contact array pads can support the solder balls 30,prior to the optical chip-to-carrier re-flow attachment. FIGS. 2A-2Fdetails the elements of the carrier 24, the alignment pin holes 34, theoptical chip and solder alignment pads 22, the solder reflowself-aligned optical chip to carrier assembly, FIG. 2D, FIG. 2Eidentifies the active optical-chip and carrier assembly attached to theflex Interconnect 16. The laminate flex Interconnect can be pre-formed(pre-manufactured) with metal traces 28. The flex is aligned andadhesive bonded to the active device side of the optical-chip. Finalflex trace to active chip connected is formed, thereon, using laserdrilled via hole through the non-conducting polymer layer, connecting tothe active-chip electrical pads. Electro-deposited metal is used to fillthe vias making them electrically conducting 44, and subsequentlyelectrically connecting the vias and chip pads to the metal traces.Photoetching process is then used to establish single point connectionsfrom one active-chip pad and its corresponding metal-ized flex-via, to asingle flex trace.

If the active optical chip is such that it requires flex metal-plane ortrace electrical connection to be made to its backside, then anelectrically conductive shim or electrical via feed-through transferchip 42 can be used. The electrically conductive shim or viafeed-through chip transfers the optical-chip backside electricalcontacts to the same level (plane) as the optical chip topsideelectrical contacts. The flex interconnect assembly is then electricallyconnected to the optical-chip and alignment carrier assembly, asdescribed above, at metal-via contact points 44.

Alternatively, the flex interconnect can be built onto the active chipand carrier assembly by repeated (sequential) polymer lamination, viadrill, electro-metal deposition, and photoetching processes. If all theopticalchip electrical contacts are on the backside of the chip, then anoptical chip to flex interconnect electrical connection can beaccomplished from the carrier base. Flex to carrier electricalconnection is accomplished using a pre-fabricated flex, and usinglead-frame edge-connection and solder attachment either before or afteroptical-chip to carrier attachment. Alternatively, the flex interconnectcan be built onto the carrier base prior to optical-chip attachment, andprior to alignment solder contact array formation, by repeated(sequential) polymer lamination, via drill, electro-metal deposition,and photo-etching processes. The solder contact array can then be addedto the flex topside, and the optical-chip subsequently solder re-flowattached and self-aligned.

Active device chip 22 is also a generally rectangular block. A replicaof the carrier solder ball array pattern is formed on the optical-chipbackside using photolithography, e.g. inferred based, electrometaldeposition, and etching processes 22, as seen in FIG. 2C. The formedoptical-chip solder contact array identifies and maintains a specificalignment between the optical-chip device aperture, i.e. laser anddetector apertures, and the carrier base 24 alignment pin locations. Inthis manner, active device chip 22 may be placed over solder ballcontact array 30 without requiring strict tolerances and then, when thesolder balls 32 melt, the solder reflow self-aligns the pattern onactive device chip 22 with the pattern on carrier 24. Thus, solder ballcontact array 30 not only affixes active device chip 22 to carrier 24,but further ensures that the array of active devices on the uppersurface of chip 22 are properly oriented with respect to alignment pinholes 34 (and thus will be properly oriented with the fiber ends when anMT connector is attached to carrier 24 using alignment pin holes 34).The solder balls may be melted by various means, including inferredradiation and zoned belt furnace re-flow.

Those skilled in the art will appreciate that the foregoing techniquemay be applied to any commercially available fiber optic connector, notjust the MT connector, by simply providing different holes or precisionguides on carrier 24 which correspond to alignment elements for theparticular connector design. Also, the active devices on chip 22 must beplaced in the same geometry as the optical fiber array in the connector.While the illustrative embodiment depicts a fiber array wherein all ofthe fiber end faces are coplanar, the present invention could even beadapted to non-coplanar fiber end face arrays, e.g., a connector bodyhaving a forward tip with a convex surface, mating with a concavesurface of an active device chip.

The active chip may be (but is not limited to) Gallium Arsenide (GaAs)based Vertical Cavity Surface Emitting Lasers (VCSEL) and GaAs basedmetal-semiconductor-metal (MSM) detectors, and commercial (or custom)PIN and/or avalanche photo-diodes arrays. The carrier can be comprisedof metal patterned ceramic, metal matrix, and metal-plastic hybridmaterial similar to commercial plastic electronic packages.

Materials that could be used to construct the carrier would be thosethat would provide high precision for critical alignment. These would betypical for printed wiring board construction including high temperatureepoxyglass or polyamide. Materials like a liquid crystal polymer (LCD)or ceramic would also provide good alignment characteristics. Opticalarray communication currently is more effectively performed using arraysof Vertical Cavity Surface Emitting Lasers (VCSEL) and photodiodes.These devices have excellent optical properties while being able to beconstructed using standard GaAs integrates circuit processes. A benefitrelative to this patent is that alignment pads placed on the backside ofthe VCSEL/Photodiode substitute shown in FIG. 2C can be done using longwavelength photolithography and optical inspection techniques since GaAsmaterial is transparent at these wavelengths.

Referring now to FIGS. 3a and 3 b, active device terminal 10 may beconveniently packaged in a housing 36 which is further adapted tosupport the particular connector being terminated, and to position theconnector with respect to termination fixture 14. FIG. 3 illustrates anMT connector 38 whose connector body extends through a hole formed in asidewall of housing 36. Mounting tabs having been attached to carrier 24to affix the termination fixture in a predefined location andorientation with respect to the hole that receives MT connector 38. Inthis manner, when MT connector 38 is inserted into the hole, thealignment pins visible in FIG. 3b and not visible in FIG. 3a, of MTconnector 38 are guided into holes 34 of carrier 24, which preciselyaligns the array of fiber end faces with the active devices on chip 22.The polymer flex interconnect 16 attached to the optical-chip topsideprotects the opticalchip apertures from excess pressure and contactdamage at the interface between the optical fiber connector endface andchip topside surface. Similarly, the polymer layer acts as a mechanicalbuffer and maintains high chip-to-connector interface reliability underharsh thermal, vibration, and shock environments. The flex also allows apredictable and reproducible separation to be achieved betweenoptical-chip apertures and the optical fiber-ends coupling. This reducessensitivity to both optical-chip design and optical coupling lossesassociated with beam divergence.

Optical components possessing only backside contacts and using theprocess of attaching the flex (electrically and mechanically) throughcontacts on the alignment carrier base, i.e. the polymer flex does notprotect the active topside on the optical-chip, will require alternateprotection against abrasion and excess pressure during assembly. This iseasily accomplished by polymer laminating (or coating) the optical-chiptopside prior to chip attachment to the alignment carrier. The depth ofinsertion of the fiber connector to the flex-chip-carrier assembly,FIGS. 2e and 3 b, may be controlled, such as by recessing theoptical-chip within the alignment carrier 24, or by using a windowedshim-stop inserted between the optical-chip carrier assembly and thefiber connector. Similarly, insertion depth and pressure may becontrolled by providing a boss or stop (formed on the housing 36) thatabuts the connector. A latch or other means can be provided to retainthe connector in the housing.

By modifying the construction of the package housing 36, and the orderof the component assembly depicted in FIG. 3a, a seal or hermetic finalpackage assembly can be achieved, FIG. 3a. In this format a sealed orhermetic optical connector feed-through 38, e.g. MT connector based, isattached to the housing 36 prior to the attachment of the optical-chipcarrier and termination fixture 14 assembly. This allows the entirehousing 36 (with optical connector feed-through) to be pre-fabricatedprior to insertion and assembly of the electrical and opticalcomponents. In this manner, the flex-optical chip-alignment carrier (16,22, 24, and 14) alignment holes 34 are inserted over the connector 38alignment pins, FIG. 3b, forming the necessary optical fiber connectorto optical chip connection. The flex electrical interface connection,using solder re-flow processes, can then be made to the electricalcircuit assembly 12. The integrity of the optical-chip-to-connectorinterface is maintained by mechanical and thermal attachment of thetermination fixture 14 to the housing 36 base. This is achieved by usingprocesses such as epoxy adhesive or solder re-flow to bonding.

The dimensions of termination fixture 14 may vary according to theparticular applications. The following exemplary dimensions are used forcompatibility with a conventional MT connector. Active device chip 22 isabout 2.0 mm wide, 2.8 mm long, and 0.6 mm high. The active devices onchip 22 are linearly aligned about 1.6 mm from a lengthwise edge of thechip with 250 μm spacings, and the device closest to a side of the chipis about 400 μm from that edge. Traces about 1.3 mm long lead from eachactive device to the contacts that become connected to the pads of flexcircuit 16. Carrier 24 is about 2.5 mm wide, 6.0 mm long, and 1.5 mmhigh. The centers of alignment holes 34 are about 4.6 mm apart, and theholes have 0.744 mm diameters. The diameters of the cavities for thesolder balls is about 150 mm.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiments, as well asalternative embodiments of the invention, will become apparent topersons skilled in the art upon reference to the description of theinvention. For example, while the description has discussed an activedevice terminal that is either a transmitter or a receiver, it wouldalso be possible to provide a transceiver wherein the terminationfixture aligns the array of fiber ends with a combined activetransmitter (e.g. laser) and detector (e.g. PIN, MSM) device chip, or byaccommodating (aligning) a passive array of device chip, e.g., having anarray of partially silvered micromirrors and attendant passive opticsused to allow both transmission of signals to the fibers from emitters,and reception of signals exiting the terminal ends of the fibers usingdetectors. It is therefore contemplated that such modifications can bemade without departing from the spirit or scope of the present inventionas defined in the appended claims.

What is claimed is:
 1. In a fiber optic device package comprising; asignal conversion device that has a plurality of optical ports and afirst plurality of electrical signal connections; an electrical circuitthat has a second plurality of electrical signal connections; a flexiblecircuit sheet that has a plurality of electrically conductive leads,each of which has first and second ends which are connected at each ofsaid first ends to at least one of said first plurality of electricalconnections and at each of said second ends to at least one of saidsecond plurality of electrical signal connections; and an opticalconnector having a plurality of optical connector fibers, wherein eachoptical connector fiber is aligned with one of said optical ports; theimprovement compromising; the insertion of said flexible circuit sheetbetween said optical connector fibers and said optical ports such thatlight passes between said optical connector fibers and said opticalports through said flexible circuit sheet.
 2. In a fiber optic devicepackage as claimed in claim 1, the improvement wherein said signalconversion device, converts electrical signals carried by saidelectrically conductive leads to optical signals that are transmitted tosaid optical ports.
 3. In a fiber optic device package as claimed inclaim 1, the improvement wherein said signal conversion device convertsoptical signal received by said optical ports to electrical signalscarried by said electrically conductive leads.
 4. In a fiber opticdevice package as claimed in claim 1, the improvement wherein saidflexible circuit sheet is inserted so that it abuts said optical ports.5. In a fiber optic device as claimed in claim 2, the improvementwherein said flexible circuit sheet is inserted so that it abuts saidoptical ports.
 6. In a fiber optic device as claimed in claim 3, theimprovement in said flexible circuit sheet is inserted so that it abutssaid optical ports.